Upper respiratory tract infections (URI's) are a significant health burden in childhood. URI's are a major reason for visits to health care providers, and up to 35% of young children at any given time are taking some over-the-counter cold medication. Unfortunately, data suggest that most of these medications have limited effectiveness. Alternative medical therapies are growing in popularity; in a recent survey of parents of children being seen by pediatricians in Seattle, Washington, 24.2% indicated that their child had been seen by an alternative medicine health care provider, and 53.3% therapies for the treatment of URI's in children. The proposed study is a randomized, double blind, placebo controlled trial of echinacea for the treatment of URI's in children 2-11 years old. The aims of the project are: to determine if echinacea shortens the duration and/or lessens the severity of URI's, if children receiving echinacea for treatment of URI's have a reduced rate of secondary bacterial infections, and to determine if the use of echinacea in patients 2-11 years old is associated with any significant side effects. A two-year study of 600 children is planned. Not only will the results of this study will determine if echinacea, the most popular medicinal herb sold in the United States, is an effective therapy for URI's in children, the study will provide a design framework for future assessments on the efficacy of other complementary and alternative medicines in children.